A rebar tying machine includes: a tying thread feeding mechanism, configured to feed a tying thread for a steel wire reeled on a steel wire reel and wind the tying thread on the rebar; and a tying thread twisting mechanism, configured to twist the tying thread wound on the rebar. The tying thread feeding mechanism and the tying thread twisting mechanism work in sequence through the operation of a starter, in order to complete a series of tying actions. For example, Chinese Invention Patent 200910203087.1, publicized on Nov. 25, 2009 under CN101586399, disclosed a rebar tying machine, including: a main sleeve having a hook pivotally mounted at its leading end, a leading end shaft nested inside the main sleeve, a spiral threaded groove formed at the leading end shaft, a nested opening passing through the main sleeve from outside to inside, a tab which is nested in the nested opening and clamped into the threaded groove, a short sleeve which is disposed on the periphery of the main sleeve and covers the tab, and a clamping unit which is formed on the short sleeve and controls the rotation of the main sleeve. The rebar tying machine with such a structure has relatively low stability during operation and is easily jammed after dirt enters the mechanism.